Lotion shampoos are widely accepted due to their ease of use. They are easily applied to and spread through the hair. Frequently, such shampoos are used as a convenient vehicle to apply pharmaceutical actives to the scalp for the treatment of dandruff or seborrheic dermatitis. One such commonly used active is selenium sulfide (Martindale, The Extra Pharmacopoeia, Pharmaceutical Press, 26th ed., 1972, pp 572-573). While being effective in treating dandruff and seborrhea, selenium sulfide shampoos tend to discolor uponn storage, particularly at high temperatures, becoming a very non-aesthetic grey-green-black color. In 1954, it was found that selenium sulfide could be stabilized and the discoloration minimized by formulating the shampoo with a buffering system (U.S. Pat. No. 2,694,669, Baldwin et al., issued Nov. 16, 1954). This approach, however, presents several product formulation negatives, particularly in terms of decreased lathering and conditioning performance, as well as limiting the range of surfactants useful in the shampoos. Thus, it would be highly desirable to formulate a color-stable shampoo containing selenium sulfide, having a pH close to the neutral range.
It has been surprisingly found by the present inventors that when peroxy oxidizing agents, such as hydrogen peroxide or sodium percarbonate, are included or used in the preparation of selenium sulfide-containing shampoo compositions, those compositions provide antidandruff efficacy and color stability without requiring the use of a buffer system.
It is an object of the present invention, therefore, to provide color-stable selenium sulfide lotion shampoos.
It is a further object of the present invention to provide selenium sulfide lotion shampoos utilizing specifically defined oxidizing agents, including hydrogen peroxide and sodium percarbonate.
It is a further object of the present invention to provide a method, utilizing peroxy oxidizing agents, for preparing colorstable selenium sulfide lotion shampoos.
It is a still further object of the present invention to provide a method for shampooing hair with improved selenium sulfide compositions.
Unless otherwise indicated, all percentages and ratios herein are by weight. Additionally, all measurements are made at 25.degree. C. in the composition or on the pure material, unless otherwise specified.